1. Field of the Invention
The present invention relates to a focal position detection apparatus applicable to the auto-focusing mechanism of an optical equipment such as a microscope, a still camera, a video camera, or the like.
2. Related Background Art
In an optical equipment such as a microscope, a still camera, or a video camera, an object image is formed on a predetermined detection surface through an objective optical system, and the formed image is picked up using an image pickup element such as a CCD, a film, or the like. Such optical equipment has an auto-focusing mechanism to photograph a sharp object image. An important portion of the auto-focusing mechanism is a focal position detection apparatus for detecting a positional shift between the imaging plane (focal position) of the objective optical system and the image pickup surface (image detection surface) of the image pickup device.